Note: Descriptions are shown in the official language in which they were submitted.
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Method for leakage detection
The invention relates to a method for leakage detection according to the
preamble
of claim 1 and to a computer program product according to the preamble of
claim
12.
If leaks occur on pipelines, it is often of great economic importance to
detect, find
and seal the leak quickly and safely. In particular in the case of pipeline
systems
that ¨ typically divided into pipeline segments ¨ have parts extending between
con-
tinents and transport large amounts of potentially environmentally harmful
products,
for example crude oil, it is generally also of great ecological importance to
quickly
seal a leak that occurs.
On the basis of the principle of conservation of mass, known methods for
leakage
detection generally fundamentally involve a mass flow balance being formed. In
principle, the amount of a transported fluid that enters a pipe section should
also
emerge from the end of said pipe section again completely, provided that there
is
no leak in the relevant section. Under idealized conditions, an imbalance in
the en-
tering mass flow and the exiting mass flow therefore indicates that there is a
leak.
The exact position of the leak along the relevant pipe section may not readily
be
ascertained in this manner, however. In addition, this idealized principle may
be
applied to real pipeline systems only inadequately. In particular the
influence of dif-
ferent environmental factors is problematic. Owing to the sometimes
considerable
length of the pipelines or pipeline segments of several thousand kilometers,
sec-
tions of for example large pipelines often run through multiple climate zones.
Most
notably temperatures along the pipeline that differ on a region-by-region
basis and,
in addition, change over time are a sometimes considerable interference
quantity
for ascertaining a mass flow balance, depending on the product that is
transported.
Owing to the thermal expansion of the fluid that is transported, which is
dependent
on the individual product in each case, the mass flow balance may turn out to
be
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negative or even positive even without a presence of a leak. The natural
volume of
the pipeline provides for a certain buffer effect in this case. If a pipeline
runs
through colder regions, the fluid transported will contract in these areas. A
similar
effect is produced by short-term local changes in the ambient temperature of
the
pipeline, for example as a result of precipitation or owing to different
levels of
shielding of the ground from sunlight because of the tilling and harvesting of
fields
in the case of agricultural land use above the pipeline. If this effect is
ignored when
ascertaining the mass flow balance, a loss of the transported fluid is
registered
even though there is no leak.
From an economic perspective, it is almost impossible to fully monitor a
pipeline
network having a great total line length and a complex ramification structure,
for
example, in respect of all the relevant factors. A leak that occurs is thus
rarely de-
tected immediately by sensors. Furthermore, environmental factors and the ther-
modynamic properties of the medium cannot usually be detected to an adequate
degree in order to be able to make exact statements regarding correction of
the
mass flow balance ascertained for a measurement section. For this reason,
various
approaches are known in order to make allowance or compensate for fluctuations
that occur by way of statistical handling of ascertained data. This is
intended to im-
prove the identification of leaks under real conditions.
In order to make allowance for thermodynamic changes along the pipeline or the
transported fluid, the approach of modelling processes that occur and relevant
in-
fluencing factors by way of a realtime model is pursued, for example.
Correspond-
ing methods are known by the name "Real Time Transient Model" (RTTM), for ex-
ample. In some cases, known methods also permit the leak to be located in a
spe-
cific area, for example by detecting propagating pressure waves that appear
when
a leak occurs.
It is always disadvantageous in this case, however, that the reliability of
the results
ascertained by statistical means is often low. This applies in particular if
only a
comparatively small amount of data is available or a single measurement needs
to
be evaluated. The high economic and ecological and also safety-relevant risk
in the
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event of a leak that is mistakenly not detected means that, when there is
doubt, the
decision made is usually to perform a manual inspection of the relevant
pipeline
section. This often requires a team of service engineers to venture over long
dis-
tances into challenging terrain, for example in order to inspect an overland
pipeline.
It is understandably desirable to avoid the associated risks to human beings
and
the environment and in some cases considerable costs.
Against this background, it is an object of the present invention to improve
the reli-
ability of leakage detection on the basis of ascertained data.
The aforementioned object is achieved by a method according to patent claim 1
and by a computer program product according to claim 12. Advantageous devel-
opments are in each case the subject matter of the dependent claims.
The method according to the proposal first involves a series of values being
ascertained that form the basis for the subsequent evaluation. The values
comprise
at least a change in the flow rate and a pressure change in the product or
medium
transported by an object carrying a flow and also a temperature value change.
Structurally, the object carrying a flow, which is in particular a pipe or a
pipeline, is
divided into one or more measurement sections. The method involves a plurality
of
measurement points now being defined on each measurement section. Preferably,
one measurement point each is arranged in the initial area and in the final
area of
the measurement section. Values for the aforementioned physical quantities
and, if
necessary, for further physical quantities are now ascertained at each of the
measurement points.
The desired values may be ascertained by way of direct and/or indirect measure-
ment of the physical quantities. As high a, in particular temporal, resolution
of the
recording as possible is advantageous in this case. Alternatively or
additionally,
however, data generated in another manner, in particular simulated, may also
be
applied as a value to the method according to the invention, or assigned to a
measurement point.
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It is self-evident that, according to the invention, as an alternative or in
addition to
ascertaining an absolute value for the relevant quantities, a relative value
and the
change in the applicable quantities may also be ascertained in each case. The
change, in particular over time, provides information about the dynamics of
pro-
cesses that occur and is thus of greater importance for the method than the
mere
absolute value of a quantity.
Preferably, the assessment of whether or not there is an unwanted loss of
volume
of the medium is essentially not based on any static considerations of the
actual
state. Instead, the method according to the invention involves in particular
the use
of a dynamic model. For that reason, primarily the change in the ascertained
quan-
tities, in particular over time, is of great importance.
The change in the flow rate of the medium, i.e of the fluid transported in the
object
carrying a flow, is in particular mass-based, but may also be understood as
volume-
based. Furthermore, the pressure change may relate to the hydrostatic pressure
and/or the dynamic pressure. The underlying temperature value, or the change
therein, relates in particular to the ambient temperature at the measurement
point,
but may alternatively or additionally also directly reflect the change in the
tempera-
ture of the medium at the measurement point. The recording of pressure and tem-
perature changes is of comparatively great importance, since the flow of the
medi-
um generally changes greatly depending on an existing temperature gradient
and/or pressure gradient.
Beyond the cited physical quantities, it is furthermore also possible to
ascertain
values for further quantities, for example for the rate of flow of the medium
or the
density thereof or for the external ambient pressure in the area of a
measurement
point.
If actual measured values are not available or are available in too small an
amount,
it may be possible to interpolate values for the desired quantities on the
basis of
measured values from the adjacent or neighboring measurement points.
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As an alternative or in addition to an actual measurement, the values at the
meas-
urement points may also be ascertained in particular by way of modelling. In
partic-
ular the object carrying a flow is modelled in this case, preferably including
the flow-
ing medium. This allows for example the occurrence of specific values for the
phys-
ical quantities of interest to be simulated, which means that their effects on
the ob-
ject carrying a flow and/or on the medium may be ascertained on the basis of
the
underlying model.
Usually, both measured values and values ascertained by way of modelling or
sim-
ulation may fundamentally be subject to an uncertainty, i.e. a random and/or
sys-
tematic error. For this reason, statements may be made using the method accord-
ing to the invention, in particular in the form of probabilities.
Instead of a realtime model or in addition to one such, values may also be
generat-
ed by way of forward modelling. This involves in particular an iterative
method be-
ing employed, by way of which the values available at a measurement point and
the effects of such values are predicted. The number of iteration steps may
funda-
mentally be chosen according to what demands are made on the accuracy of the
calculation in individual cases.
In a preferred configuration of the modelling employed, a possible trend for
the
overall system and/or for individual parameters may be approximated inter alia
by
ascertaining conditional probability values. In this context, in particular
methods of
Bayesian statistics and/or estimation methods, such as a maximum likelihood ap-
proach, may be included.
In particular, it is possible for ascertained, modelled and/or simulated data
to be
modelled in a one-dimensional model of the object carrying a flow, preferably
a
pipeline or a pipeline system, in a simplified manner. This may be accompanied
by
an in particular selective reduction of data to a specific extent and/or by
way of tar-
geted combination of data. This may moreover be based on a weighting in order
to
stipulate the extent to which the data used are adopted in the model or
influence
the modelled result. In general, a corresponding simplification down to a one-
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dimensional model permits considerably simplified and thus more reliable
detecta-
bility of the critical effects that need to be observed.
It is self-evident that a higher-dimensional model and/or a combination of
multiple
one- and/or higher-dimensional models may also be employed in a comparable
manner. In principle, the reproduction or use of the normally extensive
available da-
ta for a largely simplified model is advantageous in respect of the method
according
to the invention. An accordingly reduced representation of the present
situation, or
the likely future trend therein, permits highly reliable detection or rating
of irregulari-
ties in regard to the state and/or the operation of a pipeline system, in
particular for
a user. What level of simplification is ultimately sought in this case may be
defined
in particular on the basis of the specific application situation in individual
cases.
A realtime model and/or forward modelling of the state of the considered
object car-
rying a flow may preferably be used to determine an optimum value for the
spatial
and/or temporal density of the measurement points for capturing the data that
are
to be taken into consideration. The measurement point density is in particular
in-
homogeneously distributed over the entire considered object carrying a flow,
or a
specific measurement section. The ascertainment of an optimum density allows
an
adequate amount of data for rating the present and/or future state to be
collected
locally and/or, in relation to events, over time without, as a result of
unnecessarily
redundant capture, generating a surplus of data volume, the transmission,
storage
and processing of which is time-consuming and costly. If for example the
particular
need for reliable assessment of possibly critical situations in high-risk
areas means
that there is provision for a higher density of measurement points locally,
the mod-
elling permits a respective economically optimum degree to which adequate data
collection takes place to be determined in this regard.
If values for the underlying physical quantities are ascertained at different
meas-
urement points of the measurement section, the method involves at least one
group
of values being formed from these values. The group of values may ultimately
comprise the total set of recorded or otherwise ascertained values or may be
formed by a subgroup of these values.
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The ascertained values are supplied to a data processing device for
evaluation.
The data processing device may be a computer that is present locally close to
the
measurement section. A particular preference, however, is central processing
of
the data from different measurement points and/or measurement sections by a
common data processing device. The data processing device may furthermore also
be a network comprising multiple interacting computers. In particular, it is
preferred
for the data processing device to be provided at a physical distance from the
measurement sections to be monitored, for example in a central computer
center.
The data processing may therefore also be performed on the basis of the
principle
of a cloud service, for example.
The group of values is examined by means of the data processing device for
whether the values in the group of values form a pattern or a pattern is
formed with-
in the group of values. If a pattern is identified in the group of values by
means of
the data processing device, the pattern, in particular its type and the
strength of its
character, may be used to determine a likelihood of a presence of a leak in
the
measurement section of the object carrying a flow. This allows in particular
heuristic
leakage detection, with the result that leaks that occur in the measurement
section
under consideration may be detected even if an evaluation of the available
data us-
ing known statistical methods does not deliver reliable results.
In particular, the method according to the invention may be used to
distinguish be-
tween patterns that, on the one hand, involve a change of flow and/or a change
of
temperature of the medium as a result of environmental influences or that, on
the
other hand, are related to an unwanted loss of flow on account of a leak or
illegal
tapping. The aim in this case is to be able to react to the respective
situation as
quickly as possible in order to keep the loss of the transported medium as low
as
possible.
Preferably, a classification algorithm is applied to the group of values, or
to a pat-
tern identified in the group of values. A pattern that is present may
therefore be not
only identified but also rated in respect of categorization into different
pattern clas-
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ses. The classes are in particular related to the relevance of the pattern in
regard to
the possibility of a presence of a leak.
Alternatively or additionally, a pattern analysis algorithm may also be
applied to the
pattern, said algorithm ¨ in a similar manner to a method for image
recognition ¨ in-
terpreting the pattern on the basis of its qualities, in particular in order
to ascertain
what event is represented by the pattern and with what likelihood.
The data processing device is preferably designed accordingly in order to be
able
to execute such a classification algorithm and/or pattern analysis algorithm.
It is possible for the ascertained values to be stored in a database as a
dataset.
Such a dataset may be formed in particular by a group of values that is also
used to
carry out the evaluation for a pattern identification. Alternatively or
additionally, it is
preferred for an identified pattern to be stored in a database as a dataset
and/or for
such a pattern to be assigned to a dataset stored beforehand or in parallel.
This al-
lows such a pattern and/or the underlying values to be accessed again for a
later
analysis. In particular, a further analysis may be verified thereby.
If an evaluation of the values in a group of values that has been formed
results in a
pattern being identified and if one or more patterns is or are already stored
in a da-
tabase, the patterns may be compared with one another. Multiple stored
patterns
form a type of lookup table, in particular, in this case. A classification
algorithm ap-
plied if necessary may preferably be used to determine with which of the
stored
patterns a newly identified pattern is compared. If the size of the database
of stored
patterns, which are preferably each associated with specific events, is
sufficiently
large, the present event may be identified quickly and reliably in this manner
ac-
cording to the principle of a fingerprint comparison.
Beyond an overall pattern comparison, it is alternatively or additionally
possible for
just individual characteristics of a specific pattern defined as being
characteristic to
be compared against a newly identified pattern. In this case, the
characteristic pat-
tern is used as a criterion for the presence of a leak in the measurement
section of
the object carrying a flow. The characteristic pattern may involve in
particular aver-
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aged measured values relating to the presence of a leak. In addition, it is
also pos-
sible to use generated data, i.e data modelled and/or simulated by
computation, to
produce the characteristic pattern. In this case, the characteristic pattern
preferably
corresponds to a pattern that ideally emerges in the ascertained values when
there
is a leak. Depending on the degree of match between the newly identified
pattern
and the characteristic pattern, the data processing device may be used to make
a
statement about the likelihood of a presence of a leak in the relevant
measurement
section. If a stipulated threshold value is exceeded in this case, this may be
used in
particular as a hard criterion for the presence of a leak, so that appropriate
measures, for example a manual check or an emergency shutdown, may be initiat-
ed.
A particularly preferred configuration of the method according to the
invention pro-
vides for the data processing device to be used to apply a learning algorithm
to the
ascertained values, or to the group of values formed from this. An algorithm
with
learning capability not only results in the method becoming more informative
for the
current application, possibly with every iteration, as is already the case
with popular
statistical methods. Rather, the learning algorithm is trained by any
application and
any processing of new data. Evolutionary effects increase the reliability of a
self-
learning system of this kind over time. There is therefore a drop in the error
rate for
the identification and in particular interpretation of patterns in the
ascertained val-
ues.
Popular statistical methods for data analysis in respect of leakage detection
are
usually geared to compensating for fluctuations that occur in order to be able
to
read the desired information from the correspondingly adjusted data. In
particular
when an algorithm with learning capability is used for the data analysis, the
method
according to the invention allows leakage detection on the basis of the
occurrence
of appropriate patterns in the ascertained values even under conditions under
which known methods fail. This may be the case for example if the values used
have severe outliers, as a result of which approximations made during the
statisti-
cal treatment are wide of the mark. By contrast, the method according to the
inven-
tion involves the systematic application of empirical data to newly
ascertained val-
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ues. In particular the application of an algorithm with learning capability
allows even
events that are not detected by respective rigidly applied statistical
algorithms to be
identified on the basis of the pattern that emerges in the values.
5 In a particularly preferred configuration of the method, the ascertained
values or the
group of values that is formed is evaluated using an artificial neural
network. The
data processing device is preferably of appropriate design for this purpose.
The learning algorithm is preferably trained using stored values before being
ap-
10 plied to the ascertained values or the group of values, said stored
values relating to
events that have really occurred, in particular the actual presence of a leak,
or hav-
ing been recorded in this context. Alternatively or additionally, the learning
algo-
rithm may also be trained on the basis of simulated values. Such simulated
values
have preferably been determined by simulating a leak on the object carrying a
flow.
Training in the aforementioned manner teaches the learning algorithm to relate
specific combinations of values, or patterns in groups of values, to specific
events.
After suitable training, it is therefore possible to use the algorithm with
learning ca-
pability, by way of appropriate configuration of a query, to identify a
pattern in un-
known or new values that relates to a specific type of event, in particular
indicates
that there is a leak in the measurement section under consideration.
From a design point of view, it is preferred if the values used for the method
ac-
cording to the invention, in particular for the change in the flow rate of the
medium,
in the pressure of the medium and/or in the temperature, are ascertained
noninva-
sively in each case. This avoids introducing a measuring device, such as a
sensor,
into the interior of the object carrying a flow and thus influencing the flow
of the me-
dium inside. This would create the risk of distorting the measurement itself
and
hence also the later data evaluation. Appropriate measurement of the data is
pref-
erably carried out by means of a measuring device that is arranged on or in a
shell
of the object carrying a flow, for example the wall of a pipeline. In the case
of the
flow rate, a so-called clamp-on flowmeter is particularly suitable, which may
detect
the change in the flow of the medium inside the object carrying a flow from
outside.
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Particularly preferably, the change in flow rate is measured by means of an
acous-
tic method. This involves the flow rate, or the change therein, being
ascertained on
the basis of the propagation behavior of acoustic signals, which are
introduced from
outside, in the flowing medium. An ultrasound-based method in which the
injected
acoustic signals have an appropriately high frequency has been found to be par-
ticularly suitable. In particular, the acoustic signals are injected
contactlessly, i.e
without a mechanical transducer externally influencing the wall of the object
carry-
ing a flow.
Although the group of values examined in accordance with the method in order
to
identify a pattern is formed from the values ascertained at the measurement
points,
it is not necessarily limited just to these values. It is additionally
possible for further,
in particular generally available, data to be included, or added to the group
of val-
ues, for example regarding the present and/or forecast weather in the
surroundings
of the object carrying a flow. This may sometimes increase the significance of
the
results of the method according to the invention further.
In one preferred configuration of the method, ascertained values from
different
measurement points are transmitted to a central data processing device. The
transmission in this case preferably takes place wirelessly.
The invention furthermore also comprises a computer program product for deter-
mining a likelihood of a presence of a leak on an object carrying a flow of a
medi-
um. The computer program product is designed in particular for performing the
method for leakage detection according to the invention or for use in the
method
according to the invention. It thus comprises instructions for recognizing a
pattern in
a group of values, wherein the group of values is formed by values that are
ascer-
tained on a measurement section of the object carrying a flow and relate at
least to
a change in the flow rate of the medium, to a pressure change in the medium
and/or to a temperature change.
The invention is explained below in more detail on the basis of exemplary
embodi-
ments. All of the features described and/or shown in the drawings each form
inde-
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pendent aspects of the invention, regardless of their combination in the
exemplary
embodiments or in the dependency references in the claims.
In the drawings
Fig. 1 shows a schematic representation of an illustrative
application situa-
tion for the method according to the invention,
Fig. 2 shows a schematic representation of a further application
situation for
the method according to the invention and
Fig. 3 shows a schematic illustration of the data processing for the
method
according to the invention.
Fig. 1 shows a typical application situation for the method according to the
inven-
tion. An object 1 carrying a flow, in the form of a pipeline or a pipeline
section for
conveying a product in the form of an in particular fluidic medium, is laid
outdoors
partly above ground and partly below ground.
The detail shown represents a measurement section 2 of the considerably longer
object 1 carrying a flow. The measurement section 2 is monitored by the method
for
leakage detection according to the invention. This is accomplished by
ascertaining
a value for various physical parameters at each of two measurement points 3.
As a departure from the two measurement points 3 shown, a measurement section
2 may also have a larger associated number of measurement points 3. It is fur-
thermore certainly preferred, but not absolutely necessary according to the
inven-
tion, for the measurement points 3 for various physical quantities to be
arranged at
the same positions along the measurement section 2 of the object 1 carrying a
flow.
In general, the object 1 carrying a flow may be understood to mean an object
that is
fundamentally intended to have a medium flow through it. In this respect, it
is fun-
damentally also possible in the invention to ascertain values relating to a
meas-
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urement section 2 that does not have the medium flow through it continuously.
De-
termination and/or prediction of environmental parameters, such as a change in
the
ambient temperature, may be of interest in regard to a forthcoming
transportation of
the medium through the measurement section 2, for example.
In principle, for all of the relevant physical parameters, it is preferred for
the appli-
cable values to be ascertained noninvasively where possible, i.e without the
flowing
medium being influenced by components introduced into the object 1 carrying a
flow or the flow being disrupted in another way.
A value for the change in the flow rate of the medium is ascertained. This is
per-
formed in particular by a flowmeter 4. In the example shown in the present
case,
the preferred configuration of the flowmeter 4 is shown as a so-called clamp-
on
flowmeter, which is applied externally to the object 1 carrying a flow. The
flow rate
of the medium, or the change in said flow rate, may therefore be ascertained
non-
invasively. It is self-evident that any other type of flow measurement in
principle
may be useful for ascertaining values. The flow rate may be understood as
refer-
enced to the mass and/or the volume.
In the example shown, the flowmeter 4 is based on an acoustic principle for
meas-
uring the change in the flow rate of the medium. This involves acoustic
signals, in
particular in the ultrasonic range, being introduced into the medium through
the wall
of the object 1 carrying a flow, and their propagation speed being measured in
or-
der to draw a conclusion about the flow properties of the medium. Preferably,
the
acoustic signal is injected and/or the propagated signal is read
contactlessly, i.e.
without mechanical coupling of a transducer of the flowmeter 4 to the wall of
the ob-
ject 1 carrying a flow.
In addition, a value for the pressure change in the medium is ascertained at
each
measurement point 3. The pressure change is measured in particular by way of
an
appropriate pressure sensor 5.
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Furthermore, a temperature change is ascertained in particular by means of a
tem-
perature sensor 6. This is in particular a value for the ambient temperature,
or the
change therein, at the location of the measurement point 3. Alternatively or
addi-
tionally, a value may also be recorded away from the measurement point 3, for
ex-
ample between two measurement points 3 of a measurement section 2. In this con-
text, such a value may be ascertained for the air temperature, the ground
tempera-
ture, the temperature of the object 1 carrying a flow or of the flowing medium
itself.
In particular the influence of the ambient temperature on the medium in the
object 1
carrying a flow along the stretch may therefore be taken into consideration.
The values, in particular ascertained by measurement, for the cited and, if
neces-
sary, further physical parameters are transmitted to a data processing device
7 in
order to be subsequently evaluated further. The transmission is preferably
effected
wirelessly. It is self-evident that, alternatively or additionally, a wired
transmission
may also take place.
The data processing device 7 may, as indicated in the representation in Fig.
1, be a
central data processing device 7 positioned at a location that is remote from
the
measurement section 2. The data processing device 7 may be in the form of a
sin-
gle computer, but also in the form of a network of multiple interacting
computers. In
addition, there may also be provision for a configuration of the data
processing de-
vice 7 as a complex system having multiple computing units that operate in
parallel
and/or are hierarchically linked.
The data transmission from the measurement points 3 to the data processing de-
vice 7 may be effected in particular according to popular transmission
standards,
such as Bluetooth or WiFi, and/or via a mobile radio network. In addition,
there is
also the possibility of satellite-based communication between the measurement
point 3, or the devices for ascertaining values provided at the measurement
points
3, and the data processing device 7.
Furthermore, communication may take place between applicable communication
devices at the measurement points 3. By way of example, this permits provision
to
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be made for a powerful transmission installation, just at one measurement
point 3
or at least at a few measurement points 3, in order to transmit the
ascertained val-
ues to the data processing device 7. The at the individual measurement points
3 of
the measurement section 2 are initially transmitted over comparatively short
dis-
tances to a central measurement point 3 of this kind and from there are
transferred
to the data processing device 7. An appropriate design may also be realized by
a
separate relay station 10, which is not associated with a specific measurement
point 3 but rather is situated in the surroundings of the relevant measurement
sec-
tion 2 and hence in range of the communication devices of all of the relevant
measurement points 3.
One particular configuration of the method involves at least substantially
exclusively
data relating to the flow rate of the medium, or the change in said flow rate.
These
data are preferably delivered by flowmeters 4 and/or ascertained in a
modelling.
Particularly preferably, a network of measurement points 3, or flowmeters 4,
is fur-
thermore used that extends at least over a portion of the object 1 carrying a
flow, or
of the measurement section 2. In this case, the individual measurement points
3, or
flowmeters 4, preferably communicate with one another and/or with a data pro-
cessing device 7 wirelessly, optionally using an interposed relay station 10.
Alterna-
tively or additionally, just as in other configurations of the method, there
may also
be recourse to standard mobile radio technologies and/or provision for
satellite-
based communication.
As will be explained in even more detail below, the transmitted data are
evaluated
as part of the method according to the invention by means of the data
processing
device 7 and examined for the presence of a pattern that indicates the
presence of
a leak 8 in the examined measurement section 2. If such a leak 8 is detected,
or if a
sufficient likelihood of a presence of a leak 8 is ascertained, appropriate
measures
may be taken in a short time to provide a remedy.
In the representation in Fig. 1, such a leak 8 is indicated in the section of
the object
1 carrying a flow that runs below ground. The transported medium, which may be
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crude oil, for example, is getting into the soil 9 in an uncontrolled manner
at the po-
sition of the leak 8 and may contaminate the groundwater there, for example.
Be-
sides the economic significance of a loss of the transported medium, such a
leak 8
may entail serious ecological consequences. Extensive damage to the
environment
occurs not just in the case of catastrophic leaks 8 in which a large amount of
the
transported medium escapes in a short time. Rather, small leaks 8 that cause
only
a slow escape of the medium over time may also already be a great ecological
hazard.
Fig. 2 shows a further application situation for the method according to the
inven-
tion by way of illustration. The object 1 carrying a flow is formed by a
comparatively
complex pipe network there. The detail shown is intended to represent an exten-
sively ramified network of pipelines, in some cases of great length, purely
symboli-
cally. Apart from ramified networks of supply lines, some of which span great
dis-
tances between different regions of the earth, a larger industrial
installation, for ex-
ample a refinery, may also comprise a comparatively complex pipe network. Vari-
ous measurement sections 2 may be defined in such a highly ramified object 1
car-
rying a flow. A measurement section 2 is not necessarily defined only by the
sec-
tion of the object 1 carrying a flow between two measurement points 3, but may
al-
so comprise further areas, in which there is in particular provision for more
than two
measurement points 3. The definition of a measurement section 2 is ultimately
de-
pendent on from which measurement points 3 received values, or for which meas-
urement points 3 ascertained values, are used for the evaluation by the data
pro-
cessing device 7.
If the ramification complexity of the object 1 carrying a flow is accordingly
high, said
object may then be monitored directly by applicable sensors only with
difficulty.
Similarly to in the case of a pipeline having a very great length, complete
monitor-
ing of the system ultimately founders on the costs that would arise for an
appropri-
ate number of sensors. In addition, the partial volumes, which are in each
case flu-
idically connected to one another, in the various branches of the object 1
carrying a
flow result in interactions and buffer effects when the transported medium
propa-
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gates in the pipe network. This also hampers the evaluation of a mass flow bal-
ance.
The method according to the invention has an advantageous effect here by
detect-
ing interference events, such as the occurrence of a leak 8, in a specific
measure-
ment section 2 by identifying patterns in the ascertained values.
The influence of different temperatures on the behavior of the transported
medium
arises not only as it passes through various climate zones or on account of
different
weather conditions along a pipeline. In the example of an industrial
installation too,
it is usually the case that pipelines run along structures at different
temperatures.
For this reason, the temperature of the medium usually changes as it flows
through
the pipeline, or the pipeline network. The associated expansion or contraction
of
the medium significantly disrupts the ascertainment of a mass flow balance and
hampers the detection of an actual loss of mass, for example on account of a
leak
8 or on account of illegal tapping on the transport path.
In this regard, the method according to the invention in particular allows for
the fact
that various influencing factors usually affect the transported medium, in
particular
the prevailing pressure and/or flow rate conditions, on different timescales.
Chang-
es in the climatic or weather-related influences generally affect the medium
in pipe-
lines, in particular those running below ground, with a time delay, this being
ac-
companied by a certain inertia in the reaction of the system. By contrast,
desired
tappings of the medium, for example by end consumers, especially lead to short-
term and especially locally occurring fluctuations, which likewise need to be
taken
into consideration in an appropriate manner.
In particular desired, but unschedulable, tappings of the medium in a
measurement
section 2, for example by end consumers, may be modelled by way of appropriate
local consumption measurements and included in the method according to the in-
vention. To this end, there may be provision for suitable positioning of one
or more
measurement points 3, in particular comprising a flowmeter 4, in the vicinity
of the
known tapping point.
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The aim of the method according to the invention is to distinguish patterns in
the
ascertained values that occur on the basis of temperature and volume
fluctuations
in the medium on account of external and internal influences from patterns
that are
related to actual loss of the medium from the object 1 carrying a flow on the
transport path. The natural influences on the medium are varied and
accordingly
may be taken into consideration completely in popular statistical methods only
with
difficulty.
Fluctuations that occur are primarily related to a change in the temperature
of the
transported medium over time and in space ¨ in particular along the object 1
carry-
ing a flow. Although this is highly dependent on the ambient temperature, it
is influ-
enced by numerous other factors. Air and ground temperature are dependent on
the insolation to different degrees and affect the temperature of the medium
ac-
cordingly. By contrast, rain and cloud have a short-term cooling effect. In
addition,
in particular in the case of pipelines that run below ground, the biomass at
the sur-
face may have an effect on the temperature of the medium in the line, for
example
in the form of an insulating effect or by shielding the ground from sunlight.
This fac-
tor is also subject to sometimes short-term changes, for example as a result
of cul-
tivation and harvesting on areas used agriculturally.
If the object 1 carrying a flow is of sufficiently great extent or accordingly
complex
ramification, such as a pipeline or a pipeline network, thermodynamic changes
in
the flow properties of the transported medium generally also invariably occur
on
account of internal effects. The reasons for this are for example the
fluctuation or
change in the flow resistance on account of the shape of the line. In
particular if the
transported medium is composed of various substances, a change in the composi-
tion may additionally occur. This may also affect the flow behavior of the
medium.
Large pipelines or pipe networks may furthermore have a considerable natural
vol-
ume that is initially filled during so-called "line packing", i.e charging the
line with
the medium and building up operating pressure, before the medium comes out
again, or is tapped, at a particular point. A sufficiently large internal
volume of the
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object 1 carrying a flow additionally leads to buffer effects, even during
operation,
that allow volume-related changes in the medium to be registered only
indirectly.
Without further consideration of internal and/or external parameters, it is
thus hardly
possible to draw meaningful conclusions from a comparative measurement of the
flow rate, or the change therein, at the input and the output of a measurement
sec-
tion 2 of the object 1 carrying a flow.
Extensive tests have shown, surprisingly, that different types of patterns may
form
in the ascertained values. Some natural fluctuations may not be completely
elimi-
nated by means of popular statistical methods, even after the environmental pa-
rameters have been included, but lead to patterns in the data. These are
distin-
guished from those patterns that may be observed in the event of an actual
loss of
mass, for example owing to a leak 8, a line break or an illegal tapping of
medium on
the transport path.
This is the starting point for the invention in that these two types of
patterns are
identified and distinguished from one another. As already mentioned, the
method
involves the data processing device 7 being used, during or after the
evaluation of
the ascertained values for the change in the flow rate, in the pressure and in
the
temperature and, if necessary, in further physical quantities, to look for a
pattern in
these values.
The representation shown in Fig. 3 illustrates the basic sequence for the
evaluation
of ascertained values by the data processing device 7 for leakage detection. A
group of values 11 is initially formed from the ascertained values and is
analyzed
by the data processing device 7 for the presence of a pattern. The group of
values
11 may comprise all of the values ascertained at the measurement points 3 of a
measurement section 2 or may be a subset thereof.
If a pattern is identified in the group of values 11, the data processing
device 7 may
take this pattern as a basis for determining the likelihood of the presence of
a leak
8 in the relevant measurement section 2 of the object 1 carrying a flow. Such
a pat-
tern in the data of the group of values 11 is identified in particular by way
of an ap-
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propriate algorithm of a detection routine, similarly to in the case of
digital image
recognition.
The data processing device 7 is preferably designed to execute a
classification al-
gorithm and applies such an algorithm to the group of values 11. An identified
pat-
tern is therefore classified in respect of its type, nature and/or qualities.
As an alternative or in addition to such a classification algorithm, a pattern
analysis
algorithm may also be applied to the group of values 11 by the data processing
de-
vice 7. Such a pattern analysis algorithm may interpret the significance of
the iden-
tified pattern. This allows a statement to be made regarding what real event
is rep-
resented by the pattern that occurs in the ascertained values.
In one preferred configuration, the data processing device 7 accesses a
database
in which an identified pattern may be stored as dataset 12. The same applies
to the
ascertained values, or the group of values 11. In particular, the identified
pattern,
the group of values 11 and/or a specific really occurring event, for example
the
presence of a leak 8, may be linked with one another and stored in the
database as
datasets 12 or as a joint dataset 12.
A comparison of the pattern in the analyzed group of values 11 with one or
more
patterns stored in datasets 12 of the database allows the identified pattern
to be
quickly assigned to a group of events in the simplest case. Such a comparison
in
the manner of a fingerprint is possible in particular if the data processing
device 7
has access to datasets 12 that are classified in respect of the stored
patterns
and/or the associated events and the identified pattern may be uniquely
assigned
to one of these classes on the basis of its characteristics.
Alternatively or additionally, a characteristic, or idealized, pattern may
also be used
as a criterion that is taken as a basis for determining the likelihood of a
presence of
a leak 8 in the measurement section 2 under consideration by way of a
comparison
with the pattern identified in the group of values 11. A characteristic
pattern of this
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kind may be based on measured values from one or more measurements relating
to an event that has really occurred or else may be based on simulated values.
If there is a sufficient degree of match between the identified pattern and
the
characteristic pattern, i.e if a defined threshold value is exceeded, the
criterion for
the presence of a leak 8 may be rated as met, so that appropriate measures may
be taken.
A configuration of the method according to the invention in which the data pro-
cessing device 7 applies a learning algorithm to the ascertained values, or to
the
group of values 11, in order to identify a pattern is particularly preferred.
Alterna-
tively or additionally, an algorithm with learning capability may also be used
to
serve as a classification algorithm and/or as a pattern analysis algorithm.
Com-
pared to the previously described identification and evaluation of a pattern
in the
group of values 11 on the basis of essentially firmly prescribed criteria, an
algorithm
with learning capability has the advantage that it becomes more powerful and
more
reliable over time as a result of appropriate training with suitable data.
There is
therefore a decrease in susceptibility to error in regard to the incorrect
interpretation
of a pattern as an indicator of a leak 8 (false positive) and in regard to the
nonde-
tection of an existing leak 8 on the basis of the ascertained values (false
negative).
Such a learning algorithm is preferably trained by way of datasets 12 that
relate to
real events, in particular the presence of a leak 8, or were measured when the
rele-
vant event occurred. Such data ultimately model reality in the best way
possible, so
that the trained learning algorithm is ultimately tailored to the specific
patterns that
may arise in the ascertained values in individual cases under real conditions.
Alternatively or additionally, the learning algorithm may also be trained
using simu-
lated values, or model data. This allows the algorithm to have components
added
that relate to idealized conditions.
For optimum detection performance in regard to the identification,
classification
and/or interpretation of patterns in a group of values 11, training the
algorithm with
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a combination of real and simulated, or ideal, data may sometimes be
particularly
expedient.
In a more preferred configuration, the data processing device 7 may use an in
par-
ticular iterative method for modelling values. This involves using in
particular a
method for forward modelling in order to ascertain values that may be expected
under certain work and/or ambient conditions.
The values ascertained by way of such a modelling method may be employed in
different ways for the method according to the invention. By way of example,
the
parallel application of such a modelling method allows independent
verification of
the measured values and/or of a pattern that has emerged in the values.
Data obtained by way of the forward modelling are furthermore also suitable
for
training a learning algorithm.
Preferably, a comparison of the evaluation of real data with the modelling of
a spe-
cific trend for the system allows possible artefacts of the pattern
identification to be
determined and in particular corrected. In this way, it is preferably possible
to com-
pensate for shortcomings of the learning algorithm that emerge in this context
and
may be conditional, inter alia, on less-than-optimum prioritization during the
training
of the algorithm. Repeated use of this approach therefore continually improves
the
reliability of the pattern identification.
In addition, it is possible for the pattern-recognition-based method according
to the
invention to be serially linked with a corresponding method for modelling data
on
the basis of measured values. This allows for example a future trend to be mod-
elled on the basis of known or measured starting parameters and the risk of an
im-
minent structural failure of the object 1 carrying a flow to be assessed in
the results
thus obtained by identifying patterns that occur.
In addition to taking into consideration datasets 12 of a database in the
manner ex-
plained above, it is also possible to include data from external sources, in
particular
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generally available data, in different ways. These data are in particular
added to the
group of values 11 and/or linked with the group of values 11 in order to be
taken in-
to consideration for the evaluation. However, external data of this kind may
also be
used for a modelling and/or for training a learning algorithm. By way of
example,
the data may relate to the weather, the geological composition of the ground,
the in
particular agricultural use of areas or the like.
The evaluation of the ascertained values, or of the group of values 11 formed
there-
from, involves identifying a pattern in the group of values 11 and, if
necessary, in-
terpreting the pattern or otherwise associating it with a specific event or an
event
likelihood. Preferably, the data processing device 7 then generates an
appropriate
output 13 conveying the result of the preceding analysis, or of the method
used, for
a user.
The output 13 may be provided in different ways, preferably visually, audibly
and/or
in text form. In particular, the output 13, as shown in Fig. 3, may comprise a
warn-
ing about the presence of a leak 8. Furthermore, a status report may be
generated,
for example.
With regard to an automatically operating system, it is alternatively or
additionally
also possible for remedial measures relating to the output 13 to be
immediately
taken, for example for an alert to be delivered to maintenance and/or service
per-
sonnel.
It is self-evident in this case that it is fundamentally also possible to
combine differ-
ent outputs 13 or reactions to the result of the analysis by the method.
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List of reference signs:
1 object carrying a flow
2 measurement section
3 measurement point
4 flowmeter
5 pressure sensor 20
6 temperature sensor
7 data processing device
8 leak
9 soil
10 relay station 25
11 group of values
12 dataset
13 output
Date Recue/Date Received 2022-04-05
